The dyeing of tufted carpet material has traditionally been carried out in large vats called dye becks. These becks consist of a large vessel having a circular reel positioned at the top and means to heat the vessel contents to near boiling temperatures. Typically, about 300 to 400 feet of carpet was sewn in a continuous loop around the reel and then passed through a dye liquor in the vat until the cycle of dyeing was complete, usually 3 to 4 hours. The resulting piece of carpet became a batch, or lot, of that particular color. Needless to say, matching multiple lots produced by this method closely enough to be used adjacent to each other was practically impossible.
With the growth of the carpet industry, the move was made to continuous dyeing as was the practice in the apparel textile industry. The advantages of such a method were obvious; dyeing of larger lots in a given color, greater efficiencies in labor, energy, waste control, water use and effluent handling cost. However, experience soon showed that all types of carpet did not perform equally well in continuous dyeing processes.
A particular problem related to the yarn manufacture and tufting processes and not overcome by the normal handling of the continuous process is the phenomenon of texture banding. Although this is actually an optical phenomenon related to unequal tensions or spacing of yarns, it appears to be a color difference within the fabric of the carpet and is unacceptable in applications covering large areas.
Several techniques have been employed in the industry in an effort to eliminate these texture related bands but they have met with little success. Pre-steamers, wash systems, high wet add-on as well as modification of the dyeing chemistry have proven to be ineffective. Thus, many manufacturers have continued to dye certain constructions in smaller lots in batch type apparatus or have resorted to using pre-colored yarns to produce large lots.
Accordingly, it is one object of this invention to provide an apparatus and method whereby texture banding in carpets can be overcome. It is a further object to provide an apparatus and method for washing and treating carpet pile to eliminate optical banding in dyed carpet. It is a still further object to provide an apparatus and method for use in the continuous production of dyed carpet to wash, remove loose fibers and mechanically modify pile carpet. It is a still further object to provide an apparatus and method by which the tension and spacing of carpet pile yarns may be equalized to eliminate optical banding in dyed carpets.